Even as NASA pregares to resume space shuttle flights next May, there is growing debate about whether the orbiter fleet should be re-tired earlier than called for in the agency's current plans. Officially NASA says it plans to com-plete the international space station as close to 2010 as possible and then stop flying the shuttle. Finishing the space station, NASA officials have said, will require 28 shuttle flights spread over six years. Assuming NASA gets off three flights in 2005, the space agency would have to maintain an average flight rate of five missions per year to retire the shuttle fleet on schedule. While some agency officials believe more than 28 flights might be needed to finish the station and get it on a stable footing, others are assessing whether the program could get by with fewer flights.
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